Question

Rozwiąż układy równań metodą przeciwnych współczynników a) {4x+5y=12,3 {3x-2y=-4 b) {3x-0,2y=35 {2,5x-5y=5

Proszę o pomoc

Answer 1

a) 4x+5y=12,3   /*2

3x-2y=-4  /*5

 

8x+10y=24,6

15x-10y=-20

----------------------

23x=4,6    /:23

x=0,2

 

3x-2y=-4

3*0,2-2y=-4

-2y=-4-0,6

-2y=-4,6   /:(-2)

y=2,3

 

 

b) 3x-0,2y=35   /*(-25)

2,5x-5y=5

 

-75x+5y=-875

2,5x=5y=5

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-72,5x=-870   /:(-72,5)

x=12

 

2,5x-5y=5

2,5*12-5y=5

-5y=-25   /:(-5)

y=5

 

Answer 2

a. 4x+5y=12,3 I ·2                                        b. 3x-0,2y=35 I ·25
    3x-2y= -4 I ·5                                                2,5x-5y=5 I ·(-1)

    8x+10y=24,6                                                 75x-5y=875
    15x-10y= -20                                                 -2,5x+5y= -5
 
8x+15x+10y-10y= 24,6-20                                  75x-2,5x-5y+5y=875-5
23x=4,6                                                            72,5x=870 I ÷72,5
x= 0,2                                                               x= 12

    x= 0,2                                                           x=12
    8x+10y=24,6                                                  -2,5x+5y= -5

                                                                         x=12
      x= 0,2                                                          12·(-2,5)+5y= -5
    8·0,2+10y=24,6
                                                                         x=12
    x= 0,2                                                            -30+5y= -5
    1,6+10y=24,6
                                                                         x=12
     x= 0,2                                                           5y= -5+30
     10y= 24,6-1,6
                                                                         x=12
     x= 0,2                                                           5y= 25 I ÷5
     10y= 23 I ÷10
                                                                         x=12
     x= 0,2                                                           y=5
     y= 2,3